Apparatus for deposition of semiconductor thin layers

ABSTRACT

An apparatus for crystal growth is originally provided with at least one cavity arranged axially thereof for storing a solution containing material to be epitaxially grown on a plurality of substrates. The apparatus comprises a plurality of plate members arranged on top of one another, each of the plurality of plate members having at least one recess for accommodating the substrates, the plurality of plate members being arranged to be movable alternately relative to the remaining plate members so that the substrates in the recesses of the movable plate members are caused to contact the solution and simultaneously the solution confined in a bore of the movable plate members is caused to contact the substrate in the recesses of the stationary plate members.

United States atent m1 [75] Inventor: Hiroyuki Kobayashi, Kawasaki,

Japan [73] Assignee: Matsushita Electric Industrial Company,Limited,'Kadoma City, Osaka, Japan [22] Filed: Oct. 18, 1973 [21] Appl.N0.: 407,605

[30] Foreign Application Priority Data 0m. 19. 1972 Japan 47405114 5211.8. C1 118/421, 118/425, 148/171 [51] Int. Cl. B05c 3/00 [58] Field ofSearch 118/421, 400, 423, 425, 118/415, 500; 148/171, 172

[56] References Cited UNITED STATES PATENTS 3,665,888 5/1972 Berghet'al. 113/415 X Kobayashi V Dec. 17, 1974 [54] APPARATUS FOR DEPOSITIONOF 1 3,690,965 9/1972 Bergh et a1. 148/172 SEMICONDUCTOR THIN L E3,759,759 9/1973 Solomon 148/171 3,765,959 10/1973 Unno et a1. 148/171Primary ExaminerMorris Kaplan [5 7] ABSTRACT .An apparatus for crystalgrowth is originally provided with at least one cavity arranged axiallythereof for storing a solution containing material to be epitaxiallygrown on a plurality of substrates. The apparatus comprises a pluralityof plate members arranged on top of one another, each of the pluralityof plate members having at least one recess for accommodating thesubstrates, the plurality of plate members being arranged to be movablealternately relative to the remaining plate members so that thesubstrates in the recesses of the movable plate members are caused tocontact the solution and simultaneously the solution confined in a boreof the movable plate members is caused to contact the substrate in therecesses of the stationary plate members.

11 Claims, 38Drawing Figures PATENTEUUEBIYIQN 3854,44?

SHEET 10F 9 F/lg- (PRIOR ART) los Hoe Fig. /b (PRIOR. ART) Fig. lc(RR)0R RT) I24 I23 I2) I22 Fig. la (RR)0R ART) PAINTED-181N974 SHEET 2OF 9 N QE HEAVY NMOHS :JO SSBNMOIHL PATENTEU and] 71974 SHEET 4 BF 9APPARATUS FOR DEPOSITION OF SEMICONDUCTOR THIN LAYERS This inventionrelates to an apparatus for epitaxial growth from liquid phase and moreparticularly to an apparatus suitable for mass-production of epitaxiallygrown wafers from liquid phase.

The liquid-phase-epitaxial process has proven to be a very effectivetechnique for formation of high quality semiconductor wafers.Heretofore, various apparatus for liquid-phase-epitaxial growth havebeen developed, and an apparatus equipped with a sliding substrateholder has found widespread use because in it reproducibly highlyuniform wafers are being grown.

The prior art apparatus will be described with reference to FIGS. 1a-'ld of the accompanying drawing.

FIGS. 1a through 1d are cross-sectional views of four conventionalapparatus each equipped with a sliding substrate holder. In FIG. 10,there is shown a most typical one provided with a solution holder 101and a sliding substrate holder 102 arranged slidably in intimate contactwith the bottom surface of the solution holder 101. The slidingsubstrate holder 102 is provided with a recess 105 for accommodating asubstrate 106 therein. The solution holder includes a plurality of bores103 each of which carries a solution 104 containing material to beepitaxially grown on the substrate 106. In this prior art arrangement,the temperature of the solution is elevated to a desired predeterminedlevel, then the sliding substrate holder 102 is pushed as indicated byan arrow to bring the substrate into contact with the solution, and thesolution is allowed to cool to grow an epitaxial layer on the substrate.After the completion of the first epitaxial growth, the slidingsubstrate holder is further pushed for succeeding solution-substratecontacts, thus resulting in growth of successive epitaxial layers fromthe liquid phase on the substrate. This apparatus is disclosed in US.PAT. NO. 3,565,702 issued Feb. 23, I971 to Nelson, and also on page 109of the Applied Physics Letters, vol. 17, No. 3, 1970.

Recently an improvement of the aforementioned method, i.e., so calledsliding method had been made by Miller et al. As described in detail inJ. Appl. Phys", vol. 43, No. 6, P. 2,817, June 1972.

In spite of the excellent crystalline characteristics of wafers grown bythese apparatus, they suffer some drawbacks, one of which isnon-suitability for massproduction of wafers. Therefore, efforts havebeen made to develop apparatus suitable for mass production. In FIGS. lbthrough hi, there are shown conventional apparatus directed to this end.Referring now to FIG. 1b, there is shown an apparatus, which is similarto the apparatus of FIG. la except that a sliding substrate holder 112is provided with a plurality of recesses 115 each accommodating asubstrate 116. In operation, the sliding substrate holder 112 is pushedas indicated by an arrow, resulting in a plurality of simultaneoussubstrate-solution contacts. FIG. shows an apparatus much more suitablefor mass-production by stacking on top of each other two apparatus ofFIG. 1b. However, disadvantages are encountered in each of theseapparatus of FIGS. lb and 1c in that each requires a bulky furnace and alarge volume of solutions. Another disadvantage is that each of thewafers grown is liable to have heterogeneous crystalline characteristicsbecause it is commonly very difficult to maintain a homogeneoustemperature area within a bulky furnace. In FIG. 1d another conventionalapparatus for a massproduction of wafers is shown. The differencebetween 1 the apparatus illustrated in FIGS. 1b and 1d is that asolution holder 131 is provided with only one cavity. The disadvantagesinherent to the apparatus are the required very long operating time andlengthy furnace, so that a variation in proportions of constituents ofof the solution and horizontal temperature gradient are liable to occur.

The present invention is, therefore, intended to improveliquid-phase-epitaxial growth apparatus and contemplates to obviate theabove-mentioned disadvantages. An apparatus according to the presentinvention is originally provided with at least one cavity arrangedaxially thereof for storing a solution containing material to beepitaxially grown on a plurality of substrates. The apparatus comprisesa plurality of plate members arranged on top of one another, each of theplurality of plate members having at least one recess for accommodatingthe substrates, the plurality of plate members being arranged to beslidable alternately relative to the remaining plate members so that thesubstrates in the recesses of the slidable plate members are caused tocontact the solution and simultaneously the solution confined in a boreof the slidable plate members is caused to contact the substrate in therecesses of the stationary plate members. Because of the compactness ofthe apparatus epitaxial growths on a plurality of separate substratesare readily obtained. In practice, the thickness of the plate member iswithin a range of 0.8 to 1.5 millimeters, for example, and the size ofeach recess for accommodating the substrates is determined in accordancewith that of each of the substrates. From the above description, it isunderstood that various advantages can be derived by use of the presentapparatus. Because of the very small temperature gradient due to thevery small size and the confinement of the solution to a thin liquidlayer above the substrate, the epitaxial layer grown has a very uniformthickness throughout the whole wafer and only a small amount of solutionis required. Furthermore, epitaxial growths can be readily attained on amass production scale in a short operating time. The short operatingtime in turn makes it possible to reduce contamination of the solutionand uniform growth is obtained since there are no fluctrations ofconstituent proportions in the solution. Also, assuming that the surfaceof the solution is contaminated, this does not adversely affect theresultant wafer because the polluted solution is not used. From theforegoing description of the present invention, it is understood thatthe solution layer covering each of the substrates is very thin, forexample, about 1 millimeter.

According to our experiment, the thickness of Ga? epitaxial-grown-layerfrom a saturated solution of Ga GaP increases with increasing depth ofthe solution layer covering the substrate. In FIG. 2, there is shown therelationship between them. In this case, variations of the solutionsthickness have not adversely affected the characteristics of theresultant layers. Recently, in J. Appl. Phys, vol. 43 April 1972, P.1394, Blum et al., have disclosed a liquid-epitaxial growth apparatuswhich make possible growth of reproducibly uniform and smooth layers byusing a thin covering solution layer. In the above publication, it isdescribed that an AI Ga As grown-diffused diode having superior luminantcharacteristics is fabricated with a solution layer as thin as about 0.8millimeters.

It is accordingly an object of the present invention to provide animproved apparatus which is suitable for mass-production of epitaxiallygrown wafers during a short operating time.

Another object of the present invention is to provide an improvedapparatus with a small homogeneous temperature area at which theoperation is completed in a short time.

Still another object of the present invention is to provide an improvedapparatus of small size.

A further object of the present invention is to provide an improvedapparatus which requires a small volume of solution of the material tobe epitaxially grown on substrates.

A still further object of the present invention is to provide animproved apparatus capable of reproducibly grow highly uniform wafers.

These and other objects, advantages and features of the presentinvention will be better understood from the following description whentaken in conjunction with the accompanying drawings, in which:

FIGS. la through 1d are cross-sectional views of a prior art apparatusfor Iiquid-phase-epitaxial growth.

FIG. 2 is a graph illustrating the relationship between the thickness ofan epitaxially grown layer on a substrate and depth of solution coveringthe substrate.

FIG. 3a is a longitudinal sectional view of a first preferred embodimentfor liquid-phase-epitaxially growth apparatus prior tosubstrate-solution contact in accordance with the present invention.

FIG. 3b is a longitudinal sectional view of the first preferredembodiment, which shows the substrate in contact with the solution afterrotation of alternate plates a half cycle about the longitudinal axisthereof.

FIGS. 4a and 4b are perspective top and bottom views of a member of thefirst preferred embodiment illustrated in FIG. 3a, respectively.

FIGS. 40 and 4d are perspective and top views of another member of thefirst preferred embodiment illus trated in FIG. 3a, respectively.

FIGS. 4e and 4f are perspective top and bottom views from upper andlower sides of another member of the first preferred embodimentillustrated in FIG. 3a, respectively.

FIGS. 4g and 411 are perspective and top plan views of another member ofthe first preferred embodiment illustrated in FIG. 3a, respectively.

FIGS. 5a and 5b are perspective and top plan views of a variation of theFIG. 40 member, respectively.

FIGSfSc and 5e are perspective and top plan views of a variation of theFIG. 4g member, respectively.

FIGS. 6a and 6b are perspective and top plan views of another variationof the FIG. 4c member, respectively.

FIGS. 60 and 6d are perspective and top plan views of another variationof the FIG. 4g member, respectively.

FIGS. 7a, 7b, 7c and 7d are a perspective top view, top plan view,perspective bottom view. and bottom plan view of a variation of the FIG.60 member, respectively.

FIGS. 7e, 7f, 7g and 7h are a perspective top view,

- top plan view, perspective bottom view, and bottom plan view of avariation of FIG. 60 member, respectively.

FIG. 8a is a perspective view of a second preferred embodiment of anapparatus in accordance with the present invention.

FIGS. 8b to 8e are perspective views of members of the embodiment ofFIG. 8a.

FIG. 8fis a longitudinal sectional view of the embodiment of FIG. 80prior to substratesolution contact.

FIG. 8g is a longitudinal sectional view of the em bodiment of FIG. 8a,which shows the substrate in contact with the solution after a slidingmovement.

For detailed description of the present invention, reference is now madeto FIGS. 3a through 4h. In FIG. 3a there is shown a longitudinalsectional view of a first preferred embodiment of an apparatus accordingto the present invention, wherein a refractory tube 11 is provided fordisposing an epitaxial growth boat assembly therein. The tube 11 andassembly members of the boat assembly 30 are made of refractory materialsuch as quartz, boron nitride, high purity graphite and the like. Therefractory tube 11 is positioned a suitable refractory furnace (notshown) to be heated up to a desired predetermined temperature. Thebottom wall 12 of the refractory tube 11 is partly concaved inwardly toform a small wall hole 15a for receiving a thermocouple 17. In thepresent embodiment, the wall hole 15 I is arranged in the bottom centerportion of the tube 11 so that the thermocouple 17 might be positionedas close to a solution 31 and substrates 33 as practically possible. Thethermocouple 17 indicates only an approximate temperature of them,which, however, is adequate. The tube 11 is provided with an elongateprojection 13 on its inner bottom surface for supportingcircumferentially a base member 60, which corresponds to a lowermostmember of the growth boat 30.

In FIGS. 4e and 4f, there is shown the base member 60 wherein tworecesses 63 and 65 are formed in the upper surface of a base platemember 69 in addition to the portion supporting a center rod 61, therecess 65 being provided for accommodating the substrate 33 therein, andthe recess 63 for forming a bottom of a cavity 35. The two recesses eachlocated equidistantly from the center point of the base plate member 69and in the present embodiment the two recesses are arrangedsymmetrically with respect to the center point of the base plate member69. The center rod 61 is attached to the center portion of the uppersurface of the base plate member 69, extending axially, and beingprovided for carrying at the center portions pluralities of rotatableand stationary members, 50 and 70, respectively. A support shaft 62 isprovided for supporting circumferentially .the plurality of stationarymembers 70 relative to the base member 60, and is L-shaped with theshorter arm attached to a portion of the circumference of the base platemember 69 and with the longer armextending into the same direction asthe center rod 61. The longer arm carries the plurality of stationarymembers 70 at the bores 72 so that members 70 are fixedcircumferentially relative to the base member 60 because the center rod61 carries the members 70 at the center bores 7I. The base plate member69 has formed in the lower surface an elongate recess 67 for receivingsnugly the elongate projection 13 of the tube 11, so that the basemember 60 is forced to stay circumferentially stationary relative to thetube 11. The

lower surface of the base plate member 69 forms a concave recess 68 inthe elongate recess 67 for receiving theupper wall portion of the wellhole 15, and in the present embodiment the concave recess 68 is arrangedin the central portion of the lower surface.

In FIGS. 4a and 4b, there s shown a cap member 40. The center portion ofa cap plate member 49 forms a circular center bore 41 for rotatablyaccommodating the center rod 61 of the base member 60. The cap platemember 49 forms a cap bore 43 in addition to the center bore 41 forforming the cavity 35, and also forms a cap recess 47 in the uppersurface in addition to the center bore 41 and a cap bore 43'forreceiving a drive shaft 15, which rotated the cap member 40 about thecenter rod of the base member 60. The drive shaft is rotated by suitablemeans (not shown) positioned outside the tube 11. A rotating shaft 42 isprovided for rotating the plurality of rotatable members 50 about thecenter rod-61, and is L-shaped with the shorter arm attached to aportion of the circumference of the cap plate member 49 and with thelonger arm extending axially downward to'the opening direction of thecap re-- cess 47. The longer arm of the rotating shaft 42 carries theplurality of rotatable members 50 at the bores 52 thereof, so that thedrive shaft could rotate the rotatable members 50 about the center rod61 by way of the cap member 40.

In FIGS. 4c .and 4d, there is shown one rotatable member 50, which has arecess 55 in the upper surface thereof for accommodating the substrate33 and a bore 53 for forming the bore 35. Each of the recesses 55 andthe bores 53 are located equidistantly from the center point of themember 50, and in the present embodiment they are arranged symmetricallywith respect to the center point of the member 50. The central portionof the member 50 forms a center bore 51 for carrying snugly androtatably the center rod 61 of the base member. A projection 54 radiallyprotrudes from the circumference of the member 50, having a circularbore 52 therein through which the rotating shaft 42 of the cap member 40carries snugly and rotatably the plurality of rotatable members 50.

FIGS. 4g and 4h illustrate one stationary member 70, which is similar tothe rotatable member 50 except that a projection 74 protrudes from adifferent circumferential portion from which the projection 54 protrudesrelative to substrate recesses 55 and 75.

It is to be noted that in the first preferred embodiment the projections54 and 74 should be arranged in such a manner that they do not prevent aplurality of rotatable members from rotating through a half circle aboutthe center rod 61 of the base member 60 for the purpose of completesubstrate-solution contacts. In the first preferred embodiment, anassembly (FIG. 3a) is further provided for stirring-the solution to makeit uniform and for doping an impurity into the solution 31 from thevapor sate; The stirring assembly 20 is rotated by suitable means (notshown) positioned outside the tube 11. The upper portion of a hollowtube 24 carries a chamber 23 in which a suitable impurity having arelatively high vapor pressure is contained, and the chamber 23 and thesolution 31 communicate through openings 26 and 27 of the hollow tube24. Blades 28 are attached to a lower portion of the hollow tube 24 forthe purpose of stirring the solution.

The operation of the first preferred embodiment of the apparatus(illustrated in FIGS. 3a through 4h) is generally as follows. Thesuitable substrates 33 are placed in the recesses 65, 55 and 75 of thebase member 60, the rotatable members 50 and the stationary members 70,respectively, and then the rotatable and stationary members 50 and 70are alternately superimposed upon the base member 60, and thereafter thecap member 40 is put on the above assembly, thus forming the growth boat30. In this case it is to be noted that the growth boat is originallyarranged to form the cavity and this results in causing the axialalignment of the recesses (65, 55 and 75). A suitable charge of thematerials to be epitaxially grown then placed in the cavity 35, and thegrowth boat 30 is disposed in the refractory tube 11 such that theelongate projection 13 is snugly engaged with the recess 67, fixing theboat 30 circumferentially. The drive shaft 15 is set as shown in FIG.3a, and the refractory tube I] placed in a suitable furnace (not shown).Next, the temperature of the growth boat 30 is elevated to a desiredpredetermined degree through the tube 11. At the temperature thusattained the source material dissolves, and thereafter the solution 31is stirred by the assembly 20 to become uniform and at the same time asuitable impurity is doped into it and the assembly 20 is pulled out ofthe tube 11. The drive shaft 15 is rotated by suitable means (not shown)to rotate counterclockwise both the cap member 40 and the plurality ofthe rotatable members 50 through a half circle about the center rod 61of the base member 60, so that each of the substrates 33 carried in therecesses 55 is brought into contact with the solution confined in theeach of the bores 73, while the solution confined in the each of thebores 53 is brought into contact with each of the substrates carried inthe recesses 75. In FIG. 3b, there is shown in longitudinal sectionalview the substrates contacting the solution. Then, the temperature islowered slowly at a predetermined rate, so that a plurality of epitaxialgrowths take place at the same time, and after the completion of theepitaxial growths, the rotatable members are rotated clockwise forseparating the solutions from the substrates. After the temperature ofthe apparatus is sufficiently low, for example, room temperature, wafershaving epitaxially grown layers are taken out of the apparatus.

It is to be noted that in the present embodiment, for example, therecess 75 and the bore 73 of the stationary member are arrangedsymmetrically to each other with respect to the center point, however,it is not essential but solely for illustration. The arrangement isdiscretional on the condition that each of them be equidistant from thecenter point. The same statements are true for the other assemblymembers; In the present first embodiment, by providing suitable meanstherewith, multi-layer epitaxial growths on each of the substrates 33can be accomplished. The means is provided in the bottom of cavity 35for draining the solution after the completion of a first epitaxialgrowth, so that successive epitaxial growths on each of the substratescan be made by pouring new solution into the drained cavity 35. The newsolution is stored in a suitable means which is provided over the cavity35.

Reference is now made to FIGS. 5a and 5d, wherein there are shown avariation (FIGS. 5a and 5b) of the FIG. 4c member and a variation (FIGS.5c and 5d) of the FIG. 4g member. In this case, variations of FIGS. 4aand 4e are not illustrated, however, they could be readily perceivedfrom FIGS. 5a and 5c in view of FIGS. 4a and 4c, respectively. In FIG.5a, the modified member 250 is provided with two recesses (255, 256),each of which accommodates a substrate therein, and two bores (253, 254)each forming a portion of a cavity for storing a solution. Similarly, inFIG. 50, the modified member 270 is provided with two recesses (275,276), each of which accommodates a substrate therein, and two bores(273, 274) each forming a portion of a cavity for storing a solution. Itis understood that, in accordance with the present apparatus embodiment,the number of produced grown wafers are twice that of the firstpreferred embodiment. Moreover, addition of an other bores and recessesto each of the members of FIGS. 5a and 5c make it possible to increasethe number of epitaxially grown wafers tobe more than thrice that of thefirst embodiment. It is to be noted that in the above mentioned modifiedembodiments of the first preferred one a suitable means for draining asolution can be provided in each of the bottom portions of the cavitiesand a suitable means for storing solutions poured into the drainedcavity also can be provided over the each of the cavities.

Referring to FIGS. 6a through FIG. 6d, there are shown two kinds ofmembers which are incorporated in a still different form of the firstpreferred embodiment. In FIGS. 6a and 60 there are shown differentvariations of FIGS. 40 and 4g, respectively. FIGS. 6b and 6d are topplan views of FIGS. 6a and 6c, respectively. Itis understood that eachof the variations illustrated in FIGS.

60 and 6c is provided with one more bore as compared I the base member60 of FIG. 4e which are also equipped with this preferred embodiment,however, they are readily perceived from FIGS. 6a and 6c in view of FIG.4a and 4e, respectively. In operation, substrates are placed within eachof a plurality of recesses 355 and 375, and a first change is positionedwithin a first cavity formed by pluralities of bores 354 and 374, and asecond charge within a second cavity formed by pluralities of bores 353and 373. Then, the temperature of the growth boat is elevatedto adesired predetermined degree, so that the first and second chargesdissolve forming first and second solutions, respectively. A modifiedcap member is rotated by a suitable means similar to the drive shaft ofFIG. 3a, and the rotation in turn causes a plurality of members 350 torotate about the longitudinal axis of the boat assembly. In the presentcase, the members 350 are rotated, for example, clockwise 90 degrees sothat each of the substrates accommodated in the recesses 355 of themembers 350 is brought into contact with the first solution confined inbores 374 of the members 370. The first solution confined in each of thebores 354 is brought into contact with each of the substrates inrecesses 375, thus a first substrate-solution contact is accomplished.

After the completion of the first epitaxial growths, the members 350 arerotated counterclockwise through a half circle, resulting in anoccurence of a second substrate-solution contact in the same manner asabove described.

Reference is made to FIGS. 7a through 7h, wherein there is shown avariation (FIGS. 7a 7d) of the FIG. 60 member and a variation (FIGS. 7e7/1) of the FIG. 61 member. A member 450 (FIGS. 70 7d) is similar to themember 350 (FIGS. 60 and 6b) except that the former is provided with arecess 454 (FIGS. 70 and 7d) in the lower surface corresponding with thebore 354 of the member 350. The member 470 (FIGS. 7e 7h) is similar tothe member 370 (FIGS. 6:: and 6d) except that the former is providedwith a recess 474 (FIGS. 73 and 7h) in the lower surface correspondingwith the bore 374 (FIGS. 6c and 6d) of the latter. In the presentembodiment, esch of the recesses 454 and 474 is used for accommodatingan impurity. In operation, each of a plurality of substrates is placedwithin each of a plurality of recesses 455 (FIGS. 7a and 7b) and 475(FIGS. 7c and 7]), and then a charge is positioned within a cavityformed by pluralities of bores 453 (FIGS; 7a 7d) and 473 (FIGS. 7e 7h).The growth boat is disposed within a suitable furnace (not shown). Then,the temperature of the growth boat assembly is elevated to a desiredpredetermined degree, so that the source materials dissolve forming asolution. Following, the members 450 are rotated counterclockwisethrough about the center axis so that a first substrate-solution contactis accomplished in the same manner as described in connection with oneform of the first preferred embodiment (FIGS. 6a 6d). After completionof the first epitaxial growth, the members 450 are rotatedcounterclockwise 909 in order to dope the solution with the impurity.Then the members 450 are rotated clockwise 90 for a secondsubstratesolution contact. The resultant second epitaxial layers arecharacteristically different from the first ones.

Reference is now made to FIGS. 8a through 8f, wherein ther are shown asecond preferred embodiment of the apparatus in accordance with thepresent invention. An epitaxial growth boat 800 forms a cavity 895 whichis arranged axially thereof for storing a solu tion 870. The growth boat800 comprises a base member 841', pluralities of transverse stationary831 and slidable 821 members which are arranged alternately on top ofone another upon the base member 841, and a cap member 811 is put on theabove assembly. The epitaxial boat assembly 800 is equipped with asuitable casing or housing (not shown) which has a bore in the uppersurface forming a portion of the cavity 895 and has stoppers forstopping horizontal movement of the stationary members 831, the base 841and cap 811 members. The upper surface of the base member 841 forms arecess 845 for forming a portion of the cavity 895 and a recess 847 foraccommodating one of the substrates 860 therein. Each of the pluralityof transverse stationary members 831 is provided with a recess 837 inthe upper surface for accommodating one of the substrates 860 and isprovided with a bore 835 forming a portion of the cavity 895. Each ofthe plurality of transverse slidable members 821 is provided with arecess 823 in the upper surface for accommodating one of the substrates860 and provided with a bore 825 for forming a portion of the cavity895. It is to be noted that the bores 825 and 835 are provided in theopposite sides with respect to the cavity 895. The cap member 811 isprovided with a bore 815 forming a portion of the cavity 895.Preferably, each of the transverse stationary and slidable members isrectangular, each of the bores and recesses having a circular crosssection, each of the bores and each of the recesses being equidistantlyspaced not more than, for example, I centimeter apart, and the thicknessof each of the stationary and slidable members being, for example. about0.8 1.5 mm.

In operation, each of the substrates 860 is placed within each of therecesses, the boat 800 assembled as mentioned above, and then sourcematerials placed within the cavity 895. The boat assembly is thenequipped with the suitable casing and disposed in a suitable furnace(not shown) and its temperature is elevated to a desired predetermineddegree. At the temperature thus attained, the source materials dissolveforming a solution. Next, the plurality of slidable memhers is slid tothe direction as indicated by arrows (FIG. 8}) by suitable means (notshown) at the same time, so that each of the substrates accommodated inthe recesses 823 is brought into contact with the solution, while thesolution confined in each of the bores 825 is brought into contact witheach of the substrates accommodated in the recesses 837 and 847. Thenthe temper- EXAMPLE I This example describes the fabrication of anelectroluminescent p-n junction diode and more particularly growth of anepitaxial p-type-GaP layer on n-type-GaP layers in accordance with thefirst preferred embodiment of the apparatus of the present invention.Prior to the above-mentioned epitaxial growth, the followingpreparations are made. An n-type-GaP single crystal is fabricated by acrystal pulling method under high pressure, next, on a sliced wafer fromthe single crystal an n-type-GaP epitaxial layer is deposited by the useof the apparatus in accordance with the first preferred embodiment ofthe apparatus, wherein there is utilized a solution including 20 gramsof Ga, 2 grams of polycrystal Ga? and 2 milligrams of tellurium.After'preparing the wafers each having an n-type-GaP layer on the GaPsubstrate, an epitaxial p-type-GaP layer is further deposited on each ofthe n-type-GaP layers as described below. A plurality of the wafers isplaced in the recesses 65 (H6. 4e), 75 (H6. 4g) and 55 (FIG. 4c). Theepitaxial boat 30 is formed according to the description of thefirst'preferred embodiment. Disposed is within the cavity 35 sourcematerials which include 20 grams of Ga, 2 grams of polycrystal GaP and30 milligrams of 641 Thereafter the epitaxial growth boat 30 is placedwithin the tube 11 such that the elongate recess 67 of the base member60 is engaged with the projection 13 of the tube 11. An impuritymaterial having a high vapor pressure, in this example, zinc is providedin the chamber 23 and the stirring means 20 is arranged as shown in FIG.30. Finally, the cavity 35 is covered by the cover 19. The air in thetube 11 is completely substituted by high purity hydrogen gas and thetube 11 is placed in a suitable furnace. The temperature of theapparatus is elevated to approximately 1,020C. and then the formedsolution 31 is stirred by the stirring means 20 to make the solutionuniform. At this temperature, zinc accommodated in the chamber 23 isadded to the solution from vapor state so that the solution is dopedwith a predetermined concentration of zinc. After stirring the solutionsufficiently, the stirring means 20 is pulled out of the tube 11.Thereafter, the drive shaft is rotated counterclockwise by suitablemeans, resulting in the simultaneous rotation of a plurality of therotatable members 50 by way of the cap member 40, so that asubstrate-solution contact is achieved in the same manner as describedin detail in connection with the first preferred embodiment. In thisexample, the rotatable and stationary members each has a thickness of lmillimeter, so that the solution covering the substrate is naturally Imillimeter deep.

Thereafter, the temperature is lowered at the rate of 2.5C/min so thatepitaxial layers are grown on the substrates. When the temperature islowered to approximately 800C, the rotatable members are rotatedclockwise for the purpose of separation of the sub strates from thesolution. The epitaxial layers so obtained ar p-type and have freecarrier concentratio of 5 X 10 electrons per cubic centimeter. After thetemperature is lowered to room temperature, the formed wafers are takenout of the apparatus and then subjected to a mesa-etching process, andafter attaching ohmically electrodes thereto, being scribed and cut inthe usual manner into pellets of semiconductor devices. Thus, we haveobtained electroluminescent diodes, which emit red light by a forwardflowing current of 3 milliamperes.

EXAMPLE ll This example describes the fabrication of anotherelectroluminescent diode having high luminance according to a variedform of the first preferred embodiment of the apparatus of the presentinvention. In this example, mirror-etched n-type GaAs wafers doped withtellurium at 10 electrons per cubic centimeter are used as substrates.The substrates are placed in the recesses 355 (FIG. 6a), 375 (FIG. 60)and the recess of the modified base member of FIG. 4e. The epitaxialboat is formed according to the description of the first preferredembodiment. It is understood that the varied form of the first preferredembodiment provides two solution-containing cavities.

in the first cavity, the solution includes 20 grams of Ga, 2 grams ofGaAs, 9 milligrams of Al, and a small amount of Si for impurity, and thesolution in the sec ond cavity includes 20 grams of Ga, 2 grams of GaAs,180 milligrams of Al and a small amount of Si for impurity. Thereafter,the epitaxial growth boat is placed within the tube 11 such that theelongate recess 67 of the modified base member is engaged with theprojection 13 of the tube 11. The air in the tube 11 is completelysubstituted by high purity hydrogen gas and the tube 11 is placed in asuitable furnace. The temperature of the apparatus is elevated to 860C,resulting in melting the source materials in two cavities. After heatingthe apparatus sufficiently, that is, minimizing temperature gradientsthereof, the drive shaft 15 is, for example, clockwise rotated throughby suitable means, resulting in the simultaneous 90 rotation of aplurality of rotating members 350 by way of the modified cap member vsothat a first substrate-solution contact is achieved as described indetail in connection with the third preferred embodiment. In thisexample, the rotatable and stationary members (350, 370) each has athickness of about 1 millimeter, so that the solution covering thesubstrates is naturally about 1 millimeter deep. Thereafter, thetemperature is firstly lowered at the rate of 15C per minute, secondlyper minute so that silicon contained in the solution is firstly added asa donor and secondly as an acceptor into two layers, respectively, thusresulting in successively depositing n-type and p-type layers of GaAlAson the ntype-GaAs substrate. Next, the rotatable members 350 are rotatedcounterclockwise through a half circle about the longitudinal axis ofthe boat assembly for a second solution-substrate contact, and after thetemperature of the solution is reached at 840C, the temperature isreduced at the rate of 2C per minute, resulting in a successiveepitaxial growth on the p-type layer of GaAlAs. The epitaxial layergrown by the first substrate-solution contact has a p-n junction thereinand a molar ratio of (AlAs) containing in the layer to (GaAsAl) is about1:5. The epitaxial layer grown by the second substrate-solution contacthas a 1:2 molar ratio of (AlAs) to (GaAsAl) and also a larger energygap. Consequently, since the inner absorption of light emitted in thep-n junction is reduced due to the larger energy gap, the resultantelectroluminescent diode has a high degree of luminance.

What is claimed is:

1. Apparatus for depositing epitaxial layers on a plurality ofsubstrates from a liquid phase, which comprises:

a refractory furnace;

a refractory tube disposable internally of said furnace;

an epitaxial growth boat disposable within said refractory tube, andprovided with at least one cavity arranged axially thereof, a solutionof material to be epitaxially grown on a plurality of substratesandstored in said at least one cavity, said boat comprising a pluralityof flat members arranged on top of one another, each of said pluralityof flat members having at least one recess for accommodating saidsubstrate, alternate members of said plurality of flat members beingarranged to be movable relative to the remaining fiat members so that aplurality of substrate-solution contacts are accomplished.

2. Apparatus for depositing epitaxial layers on a plurality ofsubstrates from a liquid phase, which comprises:

a refractory furnace;

a refractory tube disposable internally of said furnace;

an epitaxial growth boat disposable within said re fractory tube, andhaving a longitudinal axis, said boat being provided with at least onecavity arranged axially with said axis, a solution of material to beepitaxially grown on a plurality of substrates and stored in said atleast one cavity, said boat comprising plurality of transverse movablemembers, each of said members having at least one first recessaccommodating said substrate therein, and at least one first bore forforming a portion of said at least one cavity, said transverse movablemembers being movable about said longitudinal axis, each of said atleast one first recess and bore located equidistantly from the centerpoint thereof, and plurality of transverse stationary members, eachhaving at least one second recess accommodating at least one secondsubstrate therein, and at least one second bore for forming a portion ofsaid at least one cavity, each of said at least one second recess andbore being located equidistantly from the center point thereof, saidplurality of movable and plurality of stationary members beingalternately arranged coaxially on top of one another such that said atleast one first and at least one second bores form said at least onecavity and such that said at least one first and at least one secondrecesses are axially arranged in at least one straight line, whereby amovement of each of said plurality of transverse movable members causessaid substrate in said at least one first recess to contact saidsolution confined in said at least one second bore and causessimultaneously said solution confined in said at least one first bore tocontact said substrate in said at least one second recess, and furthermovements of each of said plurality of transverse movable members causea plurality of substratesolution contacts.

3. Apparatus as claimed in claim 2, in which said epitaxial growth boatfurther comprises:

a flat base member, arranged coaxially in intimate contact with a firstend of the set of said pluralities of movable andstationary members,

at least two recesses formed in a first surface of said flat base memberin addition to the portion supporting a center rod, at least one ofwhich accommodates one of said substrates therein, the remaining recessbeing provided for forming a bottom of said at least one cavity, saidrecesses being each located equidistantly from the center point of saidflat base member,

said center rod attached to the central portion of said first surface ofsaid flat base member, and extending axially to the opening directionsof said recesses formed in said first surface, being provided forcarrying at their central portions said pluralities of movable andstationary members,

a shaft attached to said base plate member for fixing said plurality ofstationary members relative to said base member, and

a first base fixing means formed in a second surface of said base platemember, engageable snugly with a second base fixing means formed in theinner bottom surface of said refractory tube.

4. Apparatus as claimed in claim 3, in which said flat base member iscircular,

said shaft being L-shaped with the shorter arm attached to a portion ofthe circumference of said base member and with the longer arm extendingto the same direction as said center rod,

each of said recesses having a circular cross section,

said first base fixing means being a groove. 5. Apparatus as claimed inclaim 2, in which said epitaxial growth boat further comprises: i

a flat cap member arranged coaxially in intimate contact with the secondend of the set of said pluralities of rotatable and stationary members,the center portion of said flat cap member forming a circular cap centerbore for rotatably accommodating said center rod of said base member,

said fiat cap member forming at least one cap bore therethrough inaddition to said cap center bore for forming said at least one cavity,

said cap plate member forming a cap recess in a first surface inaddition to said center bore for receiving a drive shaft provided formoving said cap member about said center rod of said base member, and

a moving shaft attached to said cap member for moving said plurality oftransverse movable members about said center rod of said base member.

6. Apparatus as claimed in claim 5, in which said flat cap member iscircular,

said moving shaft being L-shaped with the shorter arm attached to aportion of the circumference of said cap member and with the longer armextending axially in the opening direction of said cap recess, and inwhich each of said cap bore and said cap recess have a circular crosssection.

7. Apparatus as claimed in claim 2, in which said at least one firstrecess of each of said plurality of transverse movable members is formedin a first surface thereof in addition to a first center bore,

the central portion of each of said plurality of transverse movablemembers forming said first center bore for carrying snugly and movablysaid center rod of said base member,

said first bore of each of said plurality of transverse movable membersbeing formed therethrough in addition to the portion of said firstcenter bore,

a projection radially protruding from a side edge of said movablemember, and having a circular bore therein through which a moving shaftof a cap member carries snugly and rotatably said plurality of saidmovable members about a center rod of said base member.

8. Apparatus as claimed in claim 7, in which each of said plurality ofmovable members is a circular plate, and each of said first bore andfirst recess have a circular cross section.

9. Apparatus as claimed in claim 2, in which said at least one secondrecess of each of said plurality of transverse stationary members isformed in a first surface thereof in addition to a second center bore,

the central portion of each of said plurality of transverse stationarymembers forming said second center bore to be snugly carried by a centerrod of a base member,

said second bore of each of said plurality of transversal stationarymembers being formed therethrough in addition to said second centerbore, and in which a projection radially protruding from a side edge ofsaid stationary member, having a bore therein through which said fixingshaft means of said base member carries snugly said stationary memberfor fixing relative to said base member circumferentially.

10. Apparatus as claimed in claim 9, in which each of said plurality ofstationary members is a circular plate, and each of said second bore andsecond recess having a circular cross section.

11. Apparatus as claimed in claim 2, wherein each of said plurality oftransverse movable members further comprises at least one third recessformed in the second surface thereof, each of said first and thirdrecesses being located equidistant from the center point thereof,

each of said plurality of transverse stationary members furthercomprising at least one fourth recess formed in the second surfacethereof, each of said second and fourth recesses of said transversestationary members being located equidistant from the center pointthereof, said rotatable and stationary members being alternatelyarranged on one another such that said third and fourth recesses areaxially arranged in at least one straight line.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO.5,85Z+,/+L+7 Dated December 17, 197

Inventor(s) Hirovuki Kobavasi It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

On the first page under item [19] "Kobayashi" should be --Kobayasi--Item [75] "Kobayashi" should be --Kobayasi- Signed and sealed this 1stday of July 1975.

(SEAL) Attest:

C. I'ZARSHT-TLL HAHN RUTIF C. MASON Cormissioner of Patents AttestingOfficer and Trademarks

1. Apparatus for depositing epitaxial layers on a plurality ofsubstrates from a liquid phase, which comprises: a refractory furnace; arefractory tube disposable internally of said furnace; an epitaxialgrowth boat disposable within said refractory tube, and provided with atleast one cavity arranged axially thereof, a solution of material to beepitaxially grown on a plurality of substrates and stored in said atleast one cavity, said boat comprising a plurality of flat membersarranged on top of one another, each of said plurality of flat membershaving at least one recess for accommodating said substrate, alternatemembers of said plurality of flat members being arranged to be movablerelative to the remaining flat members so that a plurality ofsubstrate-solution contacts are accomplished.
 2. Apparatus fordepositing epitaxial layers on a plurality of substrates from a liquidphase, which comprises: a refractory furnace; a refractory tubedisposable internally of said furnace; an epitaxial growth boatdisposable within said refractory tube, and having a longitudinal axis,said boat being provided with at least one cavity arranged axially withsaid axis, a solution of material to be epitaxially grown on a pluralityof substrates and stored in said at least one cavity, said boatcomprising a plurality of transverse movable members, each of saidmembers having at least one first recess accommodating said sUbstratetherein, and at least one first bore for forming a portion of said atleast one cavity, said transverse movable members being movable aboutsaid longitudinal axis, each of said at least one first recess and borelocated equidistantly from the center point thereof, and a plurality oftransverse stationary members, each having at least one second recessaccommodating at least one second substrate therein, and at least onesecond bore for forming a portion of said at least one cavity, each ofsaid at least one second recess and bore being located equidistantlyfrom the center point thereof, said plurality of movable and pluralityof stationary members being alternately arranged coaxially on top of oneanother such that said at least one first and at least one second boresform said at least one cavity and such that said at least one first andat least one second recesses are axially arranged in at least onestraight line, whereby a movement of each of said plurality oftransverse movable members causes said substrate in said at least onefirst recess to contact said solution confined in said at least onesecond bore and causes simultaneously said solution confined in said atleast one first bore to contact said substrate in said at least onesecond recess, and further movements of each of said plurality oftransverse movable members cause a plurality of substrate-solutioncontacts.
 3. Apparatus as claimed in claim 2, in which said epitaxialgrowth boat further comprises: a flat base member, arranged coaxially inintimate contact with a first end of the set of said pluralities ofmovable and stationary members, at least two recesses formed in a firstsurface of said flat base member in addition to the portion supporting acenter rod, at least one of which accommodates one of said substratestherein, the remaining recess being provided for forming a bottom ofsaid at least one cavity, said recesses being each located equidistantlyfrom the center point of said flat base member, said center rod attachedto the central portion of said first surface of said flat base member,and extending axially to the opening directions of said recesses formedin said first surface, being provided for carrying at their centralportions said pluralities of movable and stationary members, a shaftattached to said base plate member for fixing said plurality ofstationary members relative to said base member, and a first base fixingmeans formed in a second surface of said base plate member, engageablesnugly with a second base fixing means formed in the inner bottomsurface of said refractory tube.
 4. Apparatus as claimed in claim 3, inwhich said flat base member is circular, said shaft being L-shaped withthe shorter arm attached to a portion of the circumference of said basemember and with the longer arm extending to the same direction as saidcenter rod, each of said recesses having a circular cross section, saidfirst base fixing means being a groove.
 5. Apparatus as claimed in claim2, in which said epitaxial growth boat further comprises: a flat capmember arranged coaxially in intimate contact with the second end of theset of said pluralities of rotatable and stationary members, the centerportion of said flat cap member forming a circular cap center bore forrotatably accommodating said center rod of said base member, said flatcap member forming at least one cap bore therethrough in addition tosaid cap center bore for forming said at least one cavity, said capplate member forming a cap recess in a first surface in addition to saidcenter bore for receiving a drive shaft provided for moving said capmember about said center rod of said base member, and a moving shaftattached to said cap member for moving said plurality of transversemovable members about said center rod of said base member.
 6. Apparatusas claimed in claim 5, in which said flat cap member is circular, saidmoving shaFt being L-shaped with the shorter arm attached to a portionof the circumference of said cap member and with the longer armextending axially in the opening direction of said cap recess, and inwhich each of said cap bore and said cap recess have a circular crosssection.
 7. Apparatus as claimed in claim 2, in which said at least onefirst recess of each of said plurality of transverse movable members isformed in a first surface thereof in addition to a first center bore,the central portion of each of said plurality of transverse movablemembers forming said first center bore for carrying snugly and movablysaid center rod of said base member, said first bore of each of saidplurality of transverse movable members being formed therethrough inaddition to the portion of said first center bore, a projection radiallyprotruding from a side edge of said movable member, and having acircular bore therein through which a moving shaft of a cap membercarries snugly and rotatably said plurality of said movable membersabout a center rod of said base member.
 8. Apparatus as claimed in claim7, in which each of said plurality of movable members is a circularplate, and each of said first bore and first recess have a circularcross section.
 9. Apparatus as claimed in claim 2, in which said atleast one second recess of each of said plurality of transversestationary members is formed in a first surface thereof in addition to asecond center bore, the central portion of each of said plurality oftransverse stationary members forming said second center bore to besnugly carried by a center rod of a base member, said second bore ofeach of said plurality of transversal stationary members being formedtherethrough in addition to said second center bore, and in which aprojection radially protruding from a side edge of said stationarymember, having a bore therein through which said fixing shaft means ofsaid base member carries snugly said stationary member for fixingrelative to said base member circumferentially.
 10. Apparatus as claimedin claim 9, in which each of said plurality of stationary members is acircular plate, and each of said second bore and second recess having acircular cross section.
 11. Apparatus as claimed in claim 2, whereineach of said plurality of transverse movable members further comprisesat least one third recess formed in the second surface thereof, each ofsaid first and third recesses being located equidistant from the centerpoint thereof, each of said plurality of transverse stationary membersfurther comprising at least one fourth recess formed in the secondsurface thereof, each of said second and fourth recesses of saidtransverse stationary members being located equidistant from the centerpoint thereof, said rotatable and stationary members being alternatelyarranged on one another such that said third and fourth recesses areaxially arranged in at least one straight line.